For the last couple of weeks the weather has not been cooperating with the PTO’s support of NASA’s Juno mission. The last two nights were clearer but the atmosphere was very turbulent. My Friday night session did not get any useful images and out of all last night’s imagery I was able to get just one.

The bright spot just to the right of Jupiter is the moon Io. The other spot, a dark one, is near the bottom center of Jupiter. I originally thought is was atmospheric but a quick check with several planetarium programs revealed that the Jovian moon Ganymede is right there. It’s not Ganymede’s shadow as that wouldn’t cross Jupiter for another 4 hours.

My main scope is a Newtonian reflector which inverts the image, so South is at the top which conveniently matches the illustration below. Sky & Telescope magazine graciously gave me permission to use their Jupiter belt/zone illustration so I don’t have to try to make my own. Belts are the dark bands – zones are the light ones. As you can see, the spot (Ganymede?) is right on the southern border of the North polar region.

Almost any kind of Jupiter observation requires familiarity with the correct names for the various belts and zones. Here south is up; in an inverting telescope such as a Newtonian reflector, or a refractor, Schmidt-Cassegrain, or Maksutov used without a star diagonal, north will be down and east to the right. Telescopes used with a star diagonal will have north up but east and west reversed. The planet’s rotation causes features to move from east (following) to west (preceding). (c) 2015 Sky & Telescope. Used with permission.